共查询到19条相似文献,搜索用时 93 毫秒
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时频MUSIC算法利用信号的时频分布构造空间时频分布矩阵,并用该矩阵代替传统的相关矩阵进行DOA估计,可以有效抑制噪声和干扰,提高算法的稳健性。时频子空间算法突破了传统子空间算法中阵元数对估计信号个数的限制,时频点包含了信号的时频空三维信息,通过时频点的选择可直接确定信号的频率从而确定阵列流型矩阵。对于宽带信号,在进行方位估计时避免了频域搜索,减少了运算量。将时频MUSIC算法应用于二维矢量水听器垂直线阵中,充分利用矢量水听器的标、矢量信息和信号的时、频信息进行宽带信号的二维波达方位估计。仿真研究验证了算法的有效性。 相似文献
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为提高空间相关噪声场中的目标方位估计性能,提出一种基于空时相关阵联合块对角化的子空间方位估计算法.具体利用Jacobi旋转矩阵法对一组空时相关阵联合近似对角化,用联合对角化特征向量矩阵和特征值修正MUSIC(Multiple Signal Classification)等子空间算法.理论和仿真结果表明,在非相关噪声场中,基于联合对角化的子空间算法性能与常规子空间算法基本一致;而在相关噪声场中,联合对角化特征向量法能显著减小方位估计方差,提高估计性能. 相似文献
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旋转不变子空间法和多重信号分类法需假设背景噪声为独立的高斯白噪声或自相关矩阵已知,当条件不满足时算法的性能急剧下降。针对这一问题,根据矢量水听器多通道输出的特点,提出了一种基于平行因子模型的单矢量水听器方位频率联合估计方法。首先利用矢量水听器各个通道t时刻和t+1时刻的输出数据,计算声压和各振速不同组合时的四阶累积量,并构建三阶平行因子模型;然后分析了 PARAFAC 模型低秩分解的唯一性条件并利用三线性交替最小二乘算法得到了单矢量水听器阵列流形和相位延迟估计,进而得到目标的方位和频率估计。与旋转不变子空间法和多重信号分类法相比,该方法不需要子空间估计和谱峰搜索,在高斯噪声和拉普拉斯噪声背景下对多目标的分辨能力好于ESPRIT算法。仿真和实测数据的分析结果证明了算法的有效性。 相似文献
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针对传统最小均方误差谱幅度估计(MMSE—STSA.minimum mean-square error-short time spectral amplitude)语音增强算法无法有效的跟踪非平稳噪声变化的问题,对一种改进的MMSE-STSA语音增强算法进行了研究和仿真。该算法对背景噪声的估计利用加权噪声估计方法:采用一个非线性函数根据带噪语音信噪比(SNR.signal—to-noise ratio)的变化计算得到相应的加权因子并作用于带噪语音信号,对加权的带噪语音求平均得到估计的背景噪声。算法中的谱增益修正,还可以抑制低信噪比时的残留噪声以及避免对带噪语音的过抵消。实验结果表明,该方法能很好的跟踪非平稳噪声的变化,不仅在增强性能上有很好的效果,同时降低了语音的失真。 相似文献
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在信号子空间类DOA估计算法中 ,自相关矩阵估计的优劣决定了DOA估计的性能 ,但是常规自相关矩阵估计方法是对阵列输出信号做时间平均。然而对于均匀线列阵这一特殊阵型 ,其阵列输出自相关矩阵的具有To eplitz结构。根据均匀线列阵信号的时空平稳特性 ,本文提出一种时空平均的方法来改善自相关矩阵的估计质量 ,即对阵列的自相关矩阵做时间和空间两次平均 ,从而提高了DOA估计的性参 ;仿真结果表明 :在低信噪比或低快拍数的条件下能够明显提高DOA估计性能 相似文献
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A novel algorithm is proposed for simulating univariate non-Gaussian nonstationary processes (NNP) with the specified evolutionary power spectral density (EPSD)/nonstationary auto-correlation function (NACF) and first four-order time-varying marginal moments (TVMMs). The sample realizations of the target NNP are generated as the outputs from a specific time-varying auto-regressive (TVAR) model via filtering the non-Gaussian and nonstationary white noise inputs. These white noise inputs are also non-Gaussian and nonstationary, and their first four-order TVMMs are predetermined using an approach developed herein according to the specified EPSD/NACF and first four-order TVMMs of the outputs. The conventional Johnson transformation is updated to accommodate the nonstationary cases for producing desired white noise inputs. This algorithm is developed from the linear filtering method (LFM), and inherits the simplicity and high efficiency from LFM. It fills the gaps in LFM-based algorithms for simulating NNP. Two numerical examples, i.e., a ground motion acceleration and a downburst velocity, are presented to fully demonstrate the capabilities of the proposed algorithm by comparing the simulation statistics with the targets. 相似文献
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文章中把解析函数理论用于声矢量信号分析,提出了一个新概念“解析声能流”,给出了单矢量传感器输出的解析声能流表达式。并将这个新概念用于描述声矢量阵输出,得到了一种新的矢量阵输出模型“伪解析声能流”。利用该模型,推导了声矢量阵的Capon空间谱估计的表达式。理论分析和计算机仿真表明:1、解析声能流的实部和虚部具有正交的偶极子指向性,并且可以用移相的方法来旋转其主极大方向;2、在平面波和二维质点振速条件下,解析声能流将矢量叠加统一描述在它的相位中,从而可以综合描述声场的相位干涉和矢量结构;3、基于“伪解析声能流”模型,传统的Capon空间谱估计算法无需改动就可以直接用于声矢量信号处理,与传统的Capon空间谱估计算法相比,具有全空间无模糊定向能力、更低的旁瓣和对短时信号有更强的处理能力。 相似文献
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Lu Y Demirli R Cardoso G Saniie J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(11):2121-2131
In ultrasonic imaging systems, the patterns of detected echoes correspond to the shape, size, and orientation of the reflectors and the physical properties of the propagation path. However, these echoes often are overlapped due to closely spaced reflectors and/or microstructure scattering. The decomposition of these echoes is a major and challenging problem. Therefore, signal modeling and parameter estimation of the nonstationary ultrasonic echoes is critical for image analysis, target detection, and object recognition. In this paper, a successive parameter estimation algorithm based on the chirplet transform is presented. The chirplet transform is used not only as a means for time-frequency representation, but also to estimate the echo parameters, including the amplitude, time-of-arrival, center frequency, bandwidth, phase, and chirp rate. Furthermore, noise performance analysis using the Cramer Rao lower bounds demonstrates that the parameter estimator based on the chirplet transform is a minimum variance and unbiased estimator for signal-to-noise ratio (SNR) as low as 2.5 dB. To demonstrate the superior time-frequency and parameter estimation performance of the chirplet decomposition, ultrasonic flaw echoes embedded in grain scattering, and multiple interfering chirplets emitted by a large, brown bat have been analyzed. It has been shown that the chirplet signal decomposition algorithm performs robustly, yields accurate echo estimation, and results in SNR enhancements. Numerical and analytical results show that the algorithm is efficient and successful in high-fidelity signal representation. 相似文献
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《工程(英文)》2017,3(6):839-844
This research focuses on identifying the damping ratio of bridges using nonstationary ambient vibration data. The damping ratios of bridges in service have generally been identified using operational modal analysis (OMA) based on a stationary white noise assumption for input signals. However, most bridges are generally subjected to nonstationary excitations while in service, and this violation of the basic assumption can lead to uncertainties in damping identification. To deal with nonstationarity, an amplitude-modulating function was calculated from measured responses to eliminate global trends caused by nonstationary input. A natural excitation technique (NExT)-eigensystem realization algorithm (ERA) was applied to estimate the damping ratio for a stationarized process. To improve the accuracy of OMA-based damping estimates, a comparative analysis was performed between an extracted stationary process and nonstationary data to assess the effect of eliminating nonstationarity. The mean value and standard deviation of the damping ratio for the first vertical mode decreased after signal stationarization. 相似文献
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Estimations of frequency and its drift rate 总被引:1,自引:0,他引:1
Guo Wei 《IEEE transactions on instrumentation and measurement》1997,46(1):79-82
This paper presents an analysis of frequency and its drift rate estimation by the difference method, the least-squares method, and the Kalman filter. Error formulas are derived for all five noise processes: white phase, flicker phase, white frequency, flicker frequency, and random walk frequency. The error formulas show the relationship between the estimate error and the noise spectral density coefficients, the same interval τ, and the data number N. Because of the existence of some nonstationary noise processes, a large data number may not yield a good estimation. One should choose an appropriate sample interval and data number so as to control the estimate error. An optimal solution based on the Kalman filter is presented 相似文献
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V. S. Belyaev A. V. Kistovich Yu. V. Kistovich V. K. Maslov 《Measurement Techniques》1997,40(3):263-267
A nonparametric algorithm for detecting useful nonstationary signals on the background of stationary noise is described. The
algorithm properties were investigated with the aid of test signals describing monopole and dipole sources.
Translated from Izmeritel'naya Tekhnika, No. 3, pp. 45–47, March, 1997. 相似文献
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Riani J. Bergmans J.W.M. vanBeneden S. Immink A. 《IEEE transactions on magnetics》2006,42(11):3752-3759
In high-density data storage systems, noise becomes highly correlated and data dependent as a result of media noise, channel nonlinearities, and front-end filters. In such environments, conventional timing recovery schemes will exhibit large residual timing jitter and, especially, data-dependent timing jitter. This paper presents a new data-aided timing recovery algorithm for data storage systems with data-dependent noise. We derive a maximum-likelihood timing recovery scheme based on a data-dependent Gauss-Markov model of the noise. The timing recovery algorithm incorporates data-dependent noise prediction parameters in the form of linear prediction filters and prediction error variances. Moreover, because noise can be nonstationary in practice, we propose an adaptive algorithm to estimate and track the noise prediction parameters. Simulation results, for an idealized optical storage channel incorporating a simple model of media noise, illustrate the merits of our algorithm 相似文献